Promise.resolve().then(() => {
    console.log('promise1')
    const timer2 = setTimeout(() => {
        console.log('timer2')
    }, 0)
})

const timer1 = setTimeout(() => {
    console.log('timer1')
    Promise.resolve().then(() => {
        console.log('promise2')
    })
}, 0)

console.log('start')

/**
 * start,promise1,timer1, promise2, timer2
 */